With reference to FIGS. 1, 1A, and 1B, for connecting longitudinally adjacent, end-on-end sections 20a, 20b of rectangular, metal ductwork together, each end of the duct section 20a, 20b is typically provided with an integral transverse flange 22, such as a TDC® flange or a TDF® flange. Transverse flanges can be configured in different manners. In the example shown in FIGS. 1A and 1B, the flange 22 includes an upturned portion 24 extending perpendicularly outwards from the duct wall 26. A rearwardly bent portion 28, integral with the upturned portion 24 and lying generally perpendicular thereto, extends rearwards opposite the duct wall. A forewardly extending return portion 30 is integrally connected to the rearwardly bent portion 28, and is connected thereto by way of a rounded bead portion 32. A channel 34 is formed between the bead 32 and the upturned portion 24, and a similar channel 36 is formed in the duct wall opposite the channel 34, between the upturned portion 24 and the duct wall 26. (The channels 34, 36 accommodate a corner-type connector, not shown.) Further information about transverse flanges can be found, for example, in U.S. Pat. No. 4,466,641, dated Aug. 21, 1984, and in U.S. Pat. No. 6,547,287, dated Oct. 11, 2001, which also describe how the flanges are used to connect sections of duct together.
Instead of cutting, assembling, and installing a separate flange onto the ductwork, transverse flanges are typically roll formed directly onto the duct. For doing so, the edge of the metal sheeting used to form the duct is subjected to one or more roll forming operations that bend or otherwise manipulate the metal sheeting according to the desired flange configuration. The roll forming operations are carried out using a roll-forming apparatus or machine. The roll-forming machine includes a number of successively arrayed stations. As the metal sheet is passed through the roll-forming machine, each station manipulates the metal sheet according to its particular configuration.
Because roll forming operations involve the manipulation of metal sheeting, a roll-forming machine must be heavy duty, robust, and resistant to the misalignment and maladjustment of its parts. Accordingly, roll-forming machines are typically configured to produce only one type or configuration of flange, with set dimensions. If another type of flange is to be produced, or the same type of flange but with different dimensions, the machine must be manually re-tooled. For doing so, for each station, various plates and other outer portions are removed to access the station. Then, various rings, retainers, and other connectors are removed to access the tool, the tool is replaced with a new tool, and the retaining and cover portions are reattached to the device. Some roll-forming machines have been proposed for allowing the roll forming stations to be adjusted in a limited manner, but these have been based on air cylinders or hydraulic cylinders, which lack the positive location required for accurate, repetitive roll-forming operations in an industrial setting.